solar panel cleaning

Lions and tigers and ash on my solar panels, oh my!

Lorax image.jpg

What a brutal few weeks it has been. Our climate is speaking to us: We can see, taste and smell it. And, our solar panels are not happy either. Analogous to what you see on your windshield, solar panels are clouded with ash from the Mendo Complex and Carr fires (of late) and others. Yuck … makes me want to hop on a tree stump and paraphrase Dr. Seuss: I AM THE LORAX AND I SPEAK FOR THE SOLAR PANELS, FOR THE PANELS HAVE NO TONGUES, NOW LISTEN TO ME!

We monitor 200+ Repower homeowners’ solar systems 2-3 times each week, evaluating their solar generation vis-a-vis National Renewable Energy Lab projections. Though it’s at the bottom of residual impacts of the fires — we’re simply talking about electricity generation! — our solar systems are generating 10-20% less electricity over the past 10 days. Some days are worse than others … Monday (August 6) was horribly suffocating for solar panels.

What to do? Here’s an excerpt from an article we composed last summer about keeping your solar panels clean:

As solar panels have no moving parts, the main area of maintenance is to keep them clean. We recommend to check the panels periodically especially during dry periods when precipitating dust occurs with the morning dew. Dirty panels can reduce electricity production as much as 8-12% (results from Department of Energy studies vary). Most dirt can be easily removed with water sprayed from a hose or from rainfall. (Do NOT use high-pressure sprayers as it can damage the seals around the frame.) Important: Wash/spray the panels in the morning to reduce drastic temperature changes. If you cannot ascend your roof, simply spray from the ground and let gravity do the trick … a small wave of water will cleanse most dust. Do not scrub the panels with any harsh materials. If a brush is needed, make sure it has soft bristles, or opt for a common window squeegee. If you notice rapid dirt build up—or bird droppings—then more frequent cleanings are warranted.

Feel free to contact us if you have questions about how and when to clean your solar panels. And, most important, let’s hope the fires cease and our air quality improves.

A clean solar panel is a happy solar panel: Simple tips for cleaning your solar panels

In mid-June it rained. Hard. In Davis, California. Call it what you’d like: Weird weather, climate change, global warming. One thing’s for sure with the unseasonal rains: Solar panels (and their owners) were smiling on a rainy June day. Now that the rains have subsided and peak-solar generation season is in full swing, our solar panels are collecting dust and pollen and bird droppings. The panels are increasingly frowning.

What’s a solar owner to do?

Solar PV systems require modest maintenance (read: cleaning) to maximize production efficiency. Below are a few tips that will help guide your steps over the life of the system. First, the warnings: exercise great care in accessing the panels. Roof materials get unexpectedly slick. And it’s easy to damage many roofs.

Keep in mind that many owners do nothing for the entire time they own the system. Equipment failures are rare and when they occur, it’s within six months of the installation. Panels are designed to last 25-years or more; inverters last at least 12 years. In short, none of the conditions mentioned below impacts many owners. Still, for those seeking full information, keep reading.

If your home or business is powered by solar, there are three options:

1. Do nothing (i.e., let the rain cleanse your panels).

2. Do it yourself (periodically clean your panels).

3. Hire a cleaning service.

Option #1 (do nothing), obviously, generates the least amount of electricity. Option #3 (hire a professional to clean your panels) optimizes efficiency, but can be quite expensive; the cost of doing so oftentimes exceeds the value of your increased solar generation. (Researchers at UC San Diego concluded, “You definitely wouldn’t get your money back after hiring someone to wash your rooftop panels.”) Herein we focus on the most common alternative: Do it yourself.

As solar panels have no moving parts, the main area of maintenance is to keep them clean. We recommend to check the panels periodically especially during dry periods when precipitating dust occurs with the morning dew. Dirty panels can reduce electricity production as much as 8-12% (results from Department of Energy studies vary). Most dirt can be easily removed with water sprayed from a hose or from rainfall. (Do NOT use high-pressure sprayers as it can damage the seals around the frame.) Important: Wash/spray the panels in the morning to reduce drastic temperature changes. If you cannot ascend your roof, simply spray from the ground and let gravity do the trick … a small wave of water will cleanse most dust. Do not scrub the panels with any harsh materials. If a brush is needed, make sure it has soft bristles, or opt for a common window squeegee. If you notice rapid dirt build up—or bird droppings—then more frequent cleanings are warranted.

Generally, we recommend cleaning your panels every six weeks, commencing in early June (given that our last rains, typically, occur around Picnic Day) and continuing through early September. Hence, 3-4 cleanings every six weeks will suffice.

We monitor the production of 100+ solar systems in our community. Thereby, we can tell when a homeowner has cleaned their panels … solar production increases 5-6%, and then gradually decreases. In addition to our general rule-of-thumb — cleaning every six weeks during peak production season (late May through mid-September — it’s worthy to keep an eye on your web-based monitoring system to gauge if/when your panels would like a bath.

And, of course, feel free to contact us if you have questions.

A clean solar panel is a happy solar panel. (But, what’s the cost of happiness?)

One of the beauties of solar panels is their simplicity: They’re static, energy generation systems ... No moving parts, content as a sloth on your roof. Like sloths, they get dirty.

It rained -- barely -- last week. Not enough to even flinch the drought, but a decent amount of wet stuff to clean solar panels. Rain is like exercise for solar panels: Painful during (our production drops because of the clouds!), but fruitful thereafter (we're clean and powerful!).

The sole redeeming residue of climate change/weird weather/drastic drought is that solar systems are generating more energy than anticipated. For example, Repower homeowners' systems over the past two years are pumping out 6-15% more electricity than we had modeled. Little moisture in the ground (read: no fog), fewer clouds, more sunshine. A great potion for solar.

As rains diminish, should I clean (my solar panels) of should I chill? Stock answer for Yolo County homeowners: Clean them -- simply spray with a low-pressure nozzle; no soap or brushes are necessary -- three or four times a year, commencing a month after the last rains. There’s a lot of dirt in the air of our agricultural community. But, upon further review ...

... A 2013 UC San Diego study revealed it's not cost-effective -- and this was pre-drought, pre-water rate hikes -- to clean your solar panels. Synopsis:

Researchers found panels that hadn’t been cleaned, or rained on, for 145 days during a summer drought in California, lost only 7.4 percent of their efficiency. Overall, for a typical residential solar system of 5 kilowatts, washing panels halfway through the summer would translate into a mere $20 gain in electricity production until the summer drought ends—in about 2 ½ months.

Let them rest like a sloth? Perhaps. Sloths are quite happy in the sun.

P.S. - If/when you clean your solar panels, here are a few tips:

- DO NOT use high pressure sprayers as they can damage the seals around the frame. 

- Wash the panels in the morning to reduce drastic temperature changes. 

- Do not scrub the panels with any harsh materials. 

- If a brush is needed, make sure it has soft bristles. 

- If you notice rapid dirt build up—or bird droppings—then more frequent cleanings are warranted.